Strychnine bottle returned to Vic chemist

A bottle containing the potentially deadly substance strychnine that was accidentally given to a Melbourne man who wanted something to stop his child biting their nails has been returned unused.

The man returned the bottle of Tincture of Nux Vomica, which contains strychnine, to the eastern suburbs pharmacy he purchased it from on Thursday morning after hearing media reports, a Victorian health department spokesman said.

"We were facing the prospect that someone not actually hearing (media reports) and using it and a whole range of unintended consequences occurring which would have been pretty unfortunate," he told AAP.

Health authorities will now investigate how the man was given the product which was in an older-style, small brown medicine bottle, commonly used in the 1930s and 40s.

"We need to ask a bit more about why such old material has been sitting around for so long and how it came about that he did provide it to someone," the spokesman said.

He said it is likely the product was once used to stop nail biting, but not for a very long time.

Health authorities made a public plea on Wednesday for the man to return the bottle.

If ingested, strychnine causes muscular convulsions and possible death through asphyxia.